I'll give you that.
"Take screen shot! Take a Screen shot!"
My absolute favorite Simmons line is hard to choose for me. Maybe "It's going to be a VERY eventful homecoming."
In fact, the only characters who's best lines I can choose are Grif, Caboose and Sarge. In fact, I have TWO Caboose favorites, both of which take place in the same scene.
"PROTECT ME CONE!" (Which, funnily enough, is also Geoff's favorite Grif line. Geoff is his voice actor, by the way.)
"You and your cult with your tribal drumbeats! Boom-chika-boom-chika."
"Maybe it's a sword that just so happens to function like a key."
"Or maybe, it's a key all the time, and when you stick it in people, it unlocks their death."
"OOOH! Maybe, it runs on solar power!"
"Caboose, how would solar power make Tucker sick?"
"Is he a Republican?"